I have a '97 e4od(4x4 with parking brake) that for the life of me I can't get to stop leaking. I've replaced the gasket, doubled 2 up,rtv sealer, etc all with no luck as the leak keeps changing spots but mainly in the drivers side rear.
The pan and tranny both appear to not be warped.

Any ideas on how to fix it?

 

A small scratch in either mating surface will allow a leak, even with sealant...I've had luck with a flat surface such as a surface block (can be had cheap on the import machining sites) or a piece of 3/8" or thicker glass, use adhesive sandpaper 32o - 400 to slowly get past any scratches in pan. In transmission, I'd use transmission oil to lubricate sandpaper (assuming you can find self adhesive 400 grit wet dry paper) and wipe thoroughly DO NOT blow of with compressed air for obvious reasons. Actually the glass should be flat enough to give you an idea if there is any warpage. But I'd suspect a nick.

 

Put the pan, flange side down (cleaned) on a piece of glass, counter-top, etc & check for flatness. Check to see if holes are dimpled from over torque which is possible if you used 2 gaskets. Clean the holes with a wire brush & brake cleaner. A torque wrench doesn't hurt if you're chasing a re-occurring problem. I like spotlessly clean bolts with a tiny drop of blue permatex.

I like plain rubber & no sealer or RTV. Others say cork & sealer or RTV.

Others will suggest other things. Good luck.